Labour is “beyond fixable” because it has been taken over by people who want to be a “hard-left protest group” rather than a potential government, he said.

And it means “he only path to the Tories losing a majority is through the Liberal Democrats”, he said.

In an interview with ChronicleLive, Mr Farron said Labour could suffer collapse similar to the rapid decline of the Liberal Party after the first world war, when it was replaced by Labour as the leading party to the left of the Conservatives.

And he said his Liberal Democrats, the successor to the old Liberals, could emulate the success of the Liberal Party of Canada - which came third in elections in 2011 but won a majority in 2015 elections and is currently in power.

Mr Farron said: “In our system, there needs to be a strong alternative counter to the Conservatives, It once was the Liberals, then it was Labour, now it’s nobody. So who’s to say it can’t be the liberals again?”

He was speaking on Wednesday afternoon after Labour leader Jeremy Corbyn came under fire for failing to capitalise on the Conservative Government’s dramatic u-turn over National Insurance increases for the self-employed.

Chancellor Philip Hammond announced that the measure, revealed in his Budget less than a week previously, would be scrapped.

Jeremy Corbyn (Image: PA)

But critics claimed Mr Corbyn failed to land blows on the Government during his weekly question and answer session with the Prime Minister on Wednesday lunchtime.

Middlesbrough South and East Cleveland MP Labour MP Tom Blenkinsop tweeted a video of a footballer missing an open goal. And he said on Twitter: “Serious questions about holding the Govt to account need to be asked.”

Other Labour MPs compared Mr Corbyn’s performance unfavourably to former leadership contender Yvette Cooper, who mocked the Tories when she had the chance to ask her own question to the Prime Minister.

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Labour critics might point out that Mr Farron’s Liberal Democrats were part of a Conservative-led Government between 2010 and 2015.

But he said the Liberal Democrat’s long-term goal was to lead a government of their own.

“We are of the view we want to replace the Tory Party,” he said.

“We need to move into Labour’s space so there can be a decent progressive opposition party. Then we want to beat the Tories.”

This may appear a remote possibility, as the Lib Dems have only nine MPs out of 650 in the Commons.

But he said: “I am not so un-self awareness that I don’t know that with only nine MPs we are stretching things a bit to say that.

“But the other UK wide opposition party, with 200 plus MPs, is now beyond fixable. Is now in the hands of an organisation that wants it to be a hard left protest group.

“That’s fine if that’s what they want to do, but we discovered, shortly after the first world war, what happens when you miss your vocation as a party, you stop standing up for the people you should stand up for. You get replaced by somebody else.”

Liberal Democrats are calling for a fresh referendum on EU membership, giving the public a choice between accepting a deal agreed between the UK Government and the EU or simply staying in, and Mr Farron said the position had won the party respect even from people who backed Brexit.

“The policy is that the deal Theresa May comes back with should be put to the British people in good time . . . there should be a referendum on the terms of the deal versus ‘thanks but no thanks. we’ll stay put’.”